1. Field of the Invention
The present invention relates to a gelled, aqueous, metal ion formate salt composition for the prevention of seawater ingress during subsea pipeline tie-in operations and for the removal of seawater and conditioning of residual seawater film left on the pipewall during and following pipeline or flowline dewatering operations, which may involve the use of a pig or a plurality of pigs.
More particularly, the present invention relates to a method and a use of a gelled metal ion formate composition for pipeline or flowline operations. In certain embodiments, the metal ion formate starting solution is a concentrated metal ion formate solution including at least 40 wt. % of a metal ion formate or mixture thereof. The method includes the step of filling an interior or a section of a pipeline, flowline, pipeline jumper or flowline jumper with the gelled composition, where the composition includes a metal ion formate solution and an effective amount of a gelling agent sufficient to gel the solution and where the composition reduces substantially all or part of a residual water film from the interior of the pipeline, flowline, pipeline jumper or flowline jumper during a dewatering operation, or minimize or prevent the ingress of seawater into open pipeline systems or components during tie-in operations of jumpers or additional pipe, valving, manifolds, subsea pipeline architecture or flow conduits. The gelled metal ion formate salt composition is effective in reducing a water concentration of a residual film in a pipeline formed during a dewatering operation, where the dewatering operation may involve the use of a pig or multiple pigs. A slug of the gelled metal ion formate salt composition can be added to the dewatering pig train in order to achieve an improved result.
2. Description of the Related Art
To date fluids such as methanol and glycols including in gelled form are utilized for dewatering pipeline or flowline applications offshore and constantly exceed the acceptable limitations for both subsea and overboard discharge. A liquid product that Weatherford International, Inc. supplies made up of a concentrated metal ion formate solution including at least 40 wt. % of a metal ion formate or mixture thereof of potassium formate is a newly accepted liquid product generally utilized to provide hydrate control; however, the establishment of a potassium formate gel provides equally good performance in regards to dewatering applications or minimization or prevention of seawater ingress in addition to hydrate control, while being less hazardous, and less environmentally damaging.
Historically, methanol and glycols, both of which pose immediate safety concerns as well as being potentially hazardous, have been utilized for dewatering pipelines and flowlines offshore. Secondly, these fluids are considered to be toxic for overboard discharge.
Thus, there is a need in the art for compositions that address these safety issues as well as overboard discharge problems associated with chemicals for dewatering pipelines in addition to an increase in dewatering performance capabilities/potentials.